1. Field of Invention
This invention generally relates to differential pressure measuring transmitters and, more particularly, to a transmitter of this type, which is capable of compensating for the effects of static pressure changes.
2. Description of the Prior Art
Transmitters used for transmitting differential pressure values are well known, and the most used ones can be roughly grouped in three types, namely inductive, capacitive and resistive transmitters, depending on the electric output quantity being proportional to an inductance, capacitance or resistance change, respectively.
Generally, at present, all the inductance, capacitance or resistance changes are transduced by electronic processing circuits providing also for a possible linear temperature change compensation.
These transmitters, providing from certain points of view good performances and a good measuring accuracy, are affected however with the disadvantage of suffering the effect of static pressure changes acting on both the mechanical components and the electrical sensors. This effect causes a zero offset and a linear characteristic slope change (normally a reduction) of the transmitter output (zero effect and field effect).
These disadvantages are either inherent to some of these measuring instruments and, unfortunately, have to be accepted by the users due to a lack of not yet provided compensation of the static pressure effect changes or they have been reduced, normally by weighting or complicating the mechanical structure, this, however, to the detriment of the cost of the instruments.